1. Field of the Invention
The present invention relates to a cleaning device, a process cartridge incorporating the cleaning device, and an image forming apparatus which uses the cleaning device or the process cartridge incorporating the cleaning device.
In this specification, the term "image forming apparatus" is used to mean various types of apparatuses capable of forming images, including copying machines, laser beam printers, word processors and facsimile apparatuses.
2. Description of the Related Arts
Hitherto, various types of cleaning devices have been proposed and used for the purpose of removing residual or waste toner from an electrophotographic photosensitive member of an image forming apparatus, for example by means of a cleaning member.
Such a cleaning device can be constructed as an independent unit or can be incorporated in a cartridge having a photosensitive member, developing unit, and other components. In each of these cases, residual toner removed and collected by a cleaning member, such as an elastic blade or brush, is collected in a receiver or reservoir through an opening which is formed in the vicinity of the photosensitive member. A practical example of such a cleaning device is shown in FIGS. 18, 19, and 20. FIGS. 18 and 19 are a side elevational view and a plan view of a cleaning device, respectively, while FIG. 20 is an enlarged view of encircled portion denoted by reference character F in FIG. 19.
The cleaning device generally denoted by reference numeral 101 has an opening formed in the front wall of the housing 102 which faces the photosensitive drum 106. An elastic blade 103 serving as a cleaning member is disposed at the upper side of the opening, i.e., at the downstream side of the opening as viewed in the direction of movement of the surface of the photosensitive drum 106. A guide member 104 for guiding the removed developing agent is disposed at the lower side of the opening, i.e., upstream of the opening as viewed in the direction of the movement of the photosensitive drum 106. Thus, the upper and lower ends of the front opening of the housing 102 are defined by the lower end of the cleaning member 103 and the upper end of the guide member 104.
In operation, the photosensitive drum 106 is rotated in the direction of the arrow by a driving means (not shown). A latent image forming means and a developing means (both not shown) are arranged around the photosensitive drum 106 so as to form a latent image on the photosensitive drum 106 and then to develop the latent image into a visible image. The thus developed image is transferred to a transfer member 108 by means of a transfer corona charger 107. Any residual developer 109 on the photosensitive drum 106 is removed by the cleaning member 103 of the cleaning device 101 and is guided into the housing via the above-mentioned opening so as to be collected in a collecting reservoir formed by the housing. The developing agent 105 is accumulated in the reservoir until the next maintenance operation, or transported by a screw conveyor or the like to a developer waste container provided in the cleaning device 101. In some cases, the collected developer is returned to the developing device for further use. In any case, a considerable amount of collected developer is held in the collecting reservoir following a cleaning operation. Therefore, the problem is encountered that when the cleaning device is dismounted for a preventive maintenance and happens to be tilted, the developer may spill from the reservoir through the above-mentioned opening so as to contaminate the apparatus and the environment. Developer waste usually exhibits small fluidity so that the developer is not completely leveled even when the reservoir is set again to a horizontal posture. This problem is serious, particularly in process cartridges having cleaning devices therein, because the cleaning device has to be frequently removed and then inserted again for recovery operations in situations of jamming. The unleveled state of developer in the collecting reservoir may hamper the transfer of the developer removed from the photosensitive drum into the reservoir. For instance, the collected developer may be accumulated locally in the region near the opening so that further collection is impeded even though there still is an ample, vacant space in the reservoir.
In view of these drawbacks in the prior art, the present applicant has developed an apparatus in which partition plates 100 are provided in a housing defining a developer collecting reservoir so as to divide the space inside the reservoir into a plurality of sections as shown in FIG. 19, thereby limiting the movement of the developer 105 in the longitudinal direction of the cleaning member. The apparatus is discussed in U.S. Pat. No. 4,530,594 which issued on Jul. 23, 1985.
Conventionally-used developers exhibit sufficiently high fluidity due to the comparatively large sizes of particles. In recent years, however, developers having smaller particle sizes have been used, in order to cope with the demand for higher quality images. The use of such fine developer poses the following problem when the developer is used in combination with the developer collecting reservoir of the type shown in FIG. 19. Namely, in such a situation, the developer 5 introduced into the reservoir tends to be deposited and accumulated on a flat portion G (see FIG. 20) of the partition plate 100 near the entrance for the developing agent. The developer waste thus accumulated hampers further introduction of developer waste into the collecting reservoir. Consequently, the developer waste 105 is forced into the nip between the photosensitive drum 106 and the elastic blade 103 or undesirably remains on the photosensitive drum 106, resulting in a degradation of the image quality.